Correlation and path analysis between nitrogen fertilizer dosage and leaf greenness, growth, and yield traits of Coix lacryma-jobi L.

Job's tears ( Coix lacryma-jobi L.) is a functional food crop that does not yet have developed varieties; only local varieties have been released. Currently, there is no information regarding the response of local Job's tears varieties to fertilization, especially nitrogen. This study aims to determine the relationship between leaf greenness, growth, and yield traits of local Job's tears variety with nitrogen fertilizer doses. A field experiment was conducted using an experimental method at the Ciparanje Experimental Garden, Faculty of Agriculture, UNPAD Jatinangor, from November 2022 to May 2023. The soil at the research site contains low nitrogen criteria (total N = 0.12%; pH = 5.96). The experimental design was a Randomized Block Design using six treatments and four replications. The treatments were nitrogen fertilizer doses of 0, 82.5, 165, 247.5, 330, and 412.5 kg/ha. Observations were made on the leaf color chart scale, chlorophyll content index, plant height, leaf area index, number of tillers, lateral branches, panicles, seeds, and seed weight per plant. Statistical analysis used correlation tests and path analysis. The results showed a significant correlation between the dose of nitrogen fertilizer with the leaf color chart scale and the chlorophyll content index. The growth and yield traits had significant correlations with nitrogen doses. Nitrogen doses affected yield or growth traits more directly than indirectly through leaf greenness; therefore, the indicator of plant nitrogen status is obtained not only from leaf greenness but also from growth or yield components.